The default open files (nofile) limit is 1024. Let’s see how we could confirm and increase it on user and system-wide level.
Prerequisites
- Shell environment
Check and modify open files limit on user level
Step 1. Check open files limit on current user.
ulimit -n
1024
Step 2. Check soft limit.
ulimit -Sn
1024
Step 3. Check hard limit.
ulimit -Hn
1048576
Note(s):
- soft limits refer the actual limit value that affects processes, and it can be changed by them over time within the range of [0, hard limit].
- hard limits are the maximum values for soft limits, serve as a security purpose and are kernel-enforced. It can be raised only by root. A non-root user could only decrease it from the currently set one.
Step 4. Modify open files limit for all users, by adding the following lines to /etc/security/limits.conf:
* soft nofile 4096
* hard nofile 4096
Note(s): If you want to configure custom limit for the root user, replace * with root. The same goes for any other users or groups.
Check and modify open files limit on system-wide level
Step 1. Check open files limit system-wide.
cat /proc/sys/fs/file-max
Output:
65536
Step 2. Increase the open files limit available to the whole server, by adding the following line to /etc/sysctl.conf:
fs.file-max = 1631956
Step 3. Apply changes.
sysctl -p
Conclusion
Personally, I’ve never experienced any issues while messing around with soft/hard limits, but if you have any interesting story to share, please leave a comment below. On a side note, follow our official channel on Telegram.